Occupation System, new train steps, still incomplete

1 files changed, 279 insertions, 0 deletions

diff --git a/advtrains/occupation.lua b/advtrains/occupation.lua
new file mode 100644
index 0000000..f6fa6fc
--- /dev/null
+++ b/advtrains/occupation.lua
@@ -0,0 +1,279 @@
+-- occupation.lua
+--[[
+Collects and manages positions where trains occupy and/or reserve/require space
+
+Zone diagram of a train:
+              |___| |___| --> Direction of travel
+              oo oo+oo oo
+=|=======|===|===========|===|=======|===================|========|===
+ |SafetyB|CpB|   Train   |CpF|SafetyF|        Brake      |Aware   |
+[1]     [2] [3]         [4] [5]     [6]                 [7]      [8]
+
+ID|Name   |Desc
+ 0 Free    Zone that was occupied before, which has now been left
+ 1 Train   Zone where the train actually is.
+ 2 SafetyB Safety zone behind the train. extends 4m
+ 3 SafetyF Safety zone in front of the train. extends 4m
+			If a train is about to enter this zone, immediately brake it down to 2
+ 4 CpB     Backside coupling zone. If the coupling zones of 2 trains overlap, they can be coupled
+ 5 CpF     Frontside coupling zone
+ 6 Brake   Brake distance of the train. Extends to the point ~5 nodes in front
+			of the point where the train would stop if it would regularily brake now.
+ 7 Aware   Awareness zone. Extends 10-20 nodes beyond the Brake zone
+			Whenever any of the non-aware zones of other trains are detected here, the train will start to brake.
+			
+Table format:
+occ[y][x][z] = {
+	[1] = train 1 id
+	[2] = train 1 ZoneID
+//	[3] = entry seqnum*
+	...
+	[2n-1] = train n id
+	[2n  ] = train n ZoneID
+//	[3n-2] = train n id
+//	[3n-1] = train n ZoneID
+//	[3n  ] = entry seqnum*
+}
+occ_chg[n] = {
+	pos = vector,
+	train_id,
+	old_val, (0 when entry did not exist before)
+	new_val, (0 when entry was deleted)
+}
+
+*Sequence number:
+Sequence number system reserved for possible future use, but unused.
+The train will (and has to) memorize it's zone path indexes ("windows"), and do all actions that in any way modify these zone lengths
+in the movement phase (after restore, but before reporting occupations)
+((
+The sequence number is used to determine out-of-date entries to the occupation list
+The current sequence number (seqnum) is increased each step, until it rolls over MAX_SEQNUM, which is when a complete reset is triggered
+Inside a step, when a train updates an occupation, the sequence number is set to the currently active sequence number
+Whenever checking an entry for other occupations (e.g. in the aware zone), all entries that have a seqnum different from the current seqnum
+are considered not existant, and are cleared.
+Note that those outdated entries are only cleared on-demand, so there will be a large memory overhead over time. This is why in certain time intervals
+complete resets are required (however, this method should be much more performant than resetting the whole occ table each step, to spare continuous memory allocations)
+This complex behavior is required because there is no way to reliably determine which positions are _no longer_ occupied...
+))
+
+Composition of a step:
+
+1. (only when needed) restore step - write all current occupations into the table
+2. trains move
+3. trains pass new occupations to here. We keep track of which entries have changed
+4. we iterate our change lists and determine what to do
+
+]]--
+local o
+
+o.restore_required = true
+
+local MAX_SEQNUM = 65500
+local seqnum = 0
+
+local occ = {}
+local occ_chg = {}
+
+
+local function occget(p)
+	local t = occ[p.y]
+	if not t then
+		occ[p.y] = {}
+		t = occ[p.y]
+	end
+	t = t[p.x]
+	if not t then
+		t[p.x] = {}
+		t = t[p.x]
+	end
+	return t[p.z]
+end
+local function occgetcreate(p)
+	local t = occ[p.y]
+	if not t then
+		occ[p.y] = {}
+		t = occ[p.y]
+	end
+	t = t[p.x]
+	if not t then
+		t[p.x] = {}
+		t = t[p.x]
+	end
+	t = t[p.z]
+	if not t then
+		t[p.z] = {}
+		t = t[p.z]
+	end
+	return t
+end
+
+-- Resets the occupation memory, and sets the o.restore_required flag that instructs trains to report their occupations before moving
+function o.reset()
+	o.restore_required = true
+	occ = {}
+	occ_chg = {}
+	seqnum = 0
+end
+
+-- set occupation inside the restore step
+function o.init_occupation(train_id, pos, oid)
+	local t = occgetcreate(pos)
+	local i = 1
+	while t[i]
+		if t[i]==train_id then
+			break
+		end
+		i = i + 2
+	end
+	t[i] = train_id
+	t[i+1] = oid
+end
+
+function o.set_occupation(train_id, pos, oid)
+	local t = occgetcreate(pos)
+	local i = 1
+	while t[i]
+		if t[i]==train_id then
+			break
+		end
+		i = i + 2
+	end
+	local oldoid = t[i+1] or 0
+	if oldoid ~= oid then
+		addchg(pos, train_id, oldoid, oid)
+	end
+	t[i] = train_id
+	t[i+1] = oid
+end
+
+
+function o.clear_occupation(train_id, pos)
+	local t = occget(pos)
+	if not t then return end
+	local i = 1
+	local moving = false
+	while t[i] do
+		if t[i]==train_id then
+			if moving then
+				-- if, for some occasion, there should be a duplicate entry, erase this one too
+				atwarn("Duplicate occupation entry at",pos,"for train",train_id,":",t)
+				i = i - 2
+			end
+			local oldoid = t[i+1] or 0
+			addchg(pos, train_id, oldoid, 0)
+			moving = true
+		end
+		if moving then
+			t[i]   = t[i+2]
+			t[i+1] = t[i+3]
+		end
+		i = i + 2
+	end
+end
+
+local function addchg(pos, train_id, old, new)
+	occ_chg[#occ_chg + 1] = {
+		pos = pos,
+		train_id = train_id,
+		old_val = old,
+		new_val = new,
+	}
+end
+
+-- Called after all occupations have been fed in
+-- This function is doing the interesting work...
+function o.end_step()
+	count_chg = false
+	
+	for _,chg in ipairs(occ_chg) do
+		local t = occget(chg.pos)
+		if not t then
+			atwarn("o.end_step() change entry but there's no entry in occ table!",chg)
+		end
+		handle_chg(t, chg.pos, chg.train_id, chg.old_val, chg.new_val)
+	end
+	
+	seqnum = seqnum + 1
+end
+
+local function handle_chg(t, pos, train_id, old, new)
+	-- Handling the actual "change" is only necessary on_train_enter (change to 1) and on_train_leave (change from 1)
+	if new==1 then
+		o.call_enter_callback(pos, train_id)
+	elseif old==1 then
+		o.call_leave_callback(pos, train_id)
+	end
+	
+	--all other cases check the simultaneous presence of 2 or more occupations
+	if #t<=2 then
+		return
+	end
+	local blocking = {}
+	local aware = {}
+	local i = 1
+	while t[i] do
+		if t[i+1] ~= 7 then --anything not aware zone:
+			blocking[#blocking+1] = i
+		else
+			aware[#aware+1] = i
+		end
+		i = i + 2
+	end
+	if #blocking > 0 then
+		-- the aware trains should brake
+		for _, ix in ipairs(aware) do
+			atc.train_set_command(t[ix], "B2")
+		end
+		if #blocking > 1 then
+			-- not good, 2 trains interfered with their blocking zones
+			-- make them brake too
+			local txt = {}
+			for _, ix in ipairs(blocking) do
+				atc.train_set_command(t[ix], "B2")
+				txt[#txt+1] = t[ix]
+			end
+			atwarn("Trains",table.concat(txt, ","), "interfered with their blocking zones, braking...")
+			-- TODO: different behavior for automatic trains! they need to be notified of those brake events and handle them!
+			-- To drive in safety zone is ok when train is controlled by hand
+		end
+	end
+	
+end
+
+function o.call_enter_callback(pos, train_id)
+	--atprint("instructed to call enter calback")
+
+	local node = advtrains.ndb.get_node(pos) --this spares the check if node is nil, it has a name in any case
+	local mregnode=minetest.registered_nodes[node.name]
+	if mregnode and mregnode.advtrains and mregnode.advtrains.on_train_enter then
+		mregnode.advtrains.on_train_enter(pos, train_id)
+	end
+end
+function o.call_leave_callback(pos, train_id)
+	--atprint("instructed to call leave calback")
+
+	local node = advtrains.ndb.get_node(pos) --this spares the check if node is nil, it has a name in any case
+	local mregnode=minetest.registered_nodes[node.name]
+	if mregnode and mregnode.advtrains and mregnode.advtrains.on_train_leave then
+		mregnode.advtrains.on_train_leave(pos, train_id)
+	end 
+end
+
+-- Checks whether some other train (apart from train_id) has it's 0 zone here
+function o.check_collision(pos, train_id)
+	local npos = advtrains.round_vector_floor_y(pos)
+	local t = occget(npos)
+	if not t then return end
+	local i = 1
+	while t[i] do
+		if t[i]~=train_id then
+			if t[i+1] ~= 7 then
+				return true
+			end
+		end
+		i = i + 2
+	end
+	return false
+end
+
+advtrains.occ = o